Thread: Expansion Gaps - For Tongue and Groove treated Pine boards

Timber doesn’t expand in length once it’s cut out of the tree it’s grown in, only width and thickness change. That vj panelling is pretty dry and stable, 10 mm should be adequate I would think.

Not needed

Originally Posted by riverbuilder

Timber doesn’t expand in length once it’s cut out of the tree it’s grown in, only width and thickness change. That vj panelling is pretty dry and stable, 10 mm should be adequate I would think.

I forgot to mention that i will be laying across the 1.8 Meter width and not the length of the Verandah.

Hope that's still okay

Thanks again legends

I have never left expansion gaps in pine VJ and have had zero problems.

If you intend to paint or varnish the ceiling then, like fence pickets, I think that it is easiest to paint the VJ before you install it. Others will say I am crazy...

Just interested to know why you are going crosswise?
I did my veranda ceiling (1916 house) and I went lengthwise, like the original.

Originally Posted by Lappa

Just interested to know why you are going crosswise?
I did my veranda ceiling (1916 house) and I went lengthwise, like the original.

I have a number of reasons:

My house is a weatherboard facia construction (15 years old) and the weatherboard and the VJ going the same way didn't have the contrast that i was looking for.

The second reason is that one of my Verandahs is nearly ten meters long and i didn't want to accentuate the visual appearance of being long and thin and crossways would make it look shorter and wider.

The third reason is that I would not have any visible joints in the long lengths that could look unsightly if they gapped up a little (all ends hidden behind the perimeter trim).

Forth, is that although I am the father of three sons i find it very difficult to get any help of them and the short lengths are easier to install by myself.

Fifth, and Importantly, my missus has been searching the internet for direction of boards and she has seen (some, not many) verandahs with the boards running cross ways and that's how she wanted it.

Sixth, I have done a small area (approx 3.5 Meters long and 1.8M wide) as a test area prior to undertaking quite a project all around my house and I think it looks great.

I have tried to attach a picture of the test area to show you but i cannot upload to the site.

Anyway Im sure you get the idea. Out of interest do you know why are the boards fitted length ways? only i could find nothing explaining the direction of fit on the internet

Thanks again

Mumbo Jumbo

I have no idea why they are fitted lengthwise. I just followed what was there. Interestingly my veranda floorboards (tongue and groove) run out from the house (1.8m) rather than lengthwise as you see on a lot of verandas and decks these days.
The reason I see for that is it allows run off from the rain which reaches the boards with driving rain.

Originally Posted by Lappa

I have no idea why they are fitted lengthwise. I just followed what was there. Interestingly my veranda floorboards (tongue and groove) run out from the house (1.8m) rather than lengthwise as you see on a lot of verandas and decks these days.
The reason I see for that is it allows run off from the rain which reaches the boards with driving rain.

Thinking about it now, it makes sense for the boards to run length ways because the roof trusses run out from the house so they can fix the boards straight up to the trusses, where as i had to install timbers runners/battens under the trusses to fix the cross-ways boards to.

Cross-ways = Extra timber, fixings and work.

But i do like the look of it.

With such a long run of boards be mindful of creep getting you out of square.
Set out a square line in the most obvious area like say above the front entry and then mark some parallel lines say every 3 metres back to where you are starting and then reference these marks as you go to ensure you remain square with necessary micro adjustments as you go rather than getting towards the end of your run and finding your 10 plus mm out of parallel to you finish point which will cause you grief

Originally Posted by Beardy

With such a long run of boards be mindful of creep getting you out of square.
Set out a square line in the most obvious area like say above the front entry and then mark some parallel lines say every 3 metres back to where you are starting and then reference these marks as you go to ensure you remain square with necessary micro adjustments as you go rather than getting towards the end of your run and finding your 10 plus mm out of parallel to you finish point which will cause you grief

Great advice! Thank you very much.

If your boards grow or shrink by only 0.25% (which will certainly happen, maybe even a bit more) than this results in ~24mm difference for the length of 950 cm. So, your 10mm expansion gap would not be sufficient. However, that gap won't help you anyway because with that much movement the boards are likely to loosen over time.
I wouldn't push the boards tightly together, just loosely joined with about half a millimeter of air per board. This gives each board some room to work with. If your boards are 120mm wide, you'll get about 40mm extra for movement this way over the whole 950 cm. The expansion gap should be there as well; 8 to 10mm will be sufficient for this setup.

Originally Posted by AndyJ

If your boards grow or shrink by only 0.25% (which will certainly happen, maybe even a bit more) than this results in ~24mm difference for the length of 950 cm. So, your 10mm expansion gap would not be sufficient. However, that gap won't help you anyway because with that much movement the boards are likely to loosen over time.
I wouldn't push the boards tightly together, just loosely joined with about half a millimeter of air per board. This gives each board some room to work with. If your boards are 120mm wide, you'll get about 40mm extra for movement this way over the whole 950 cm. The expansion gap should be there as well; 8 to 10mm will be sufficient for this setup.

Sorry, Andy, but I must disagree. Perhaps you are referencing a situation where theory does not reflect practice.

VJ panelling has been around for well over 100 years and in most parts of the country. It is ubiquitous in the classical Queenslanders and in Tasmanian cottages - for walls, ceilings, screens and built in furniture. Generally the material was ½ inch thick, sometimes ⅜ and early examples often used now exotic timbers like red cedar, port jackson pine, King Billy pine, etc. Plantation pine now dominates. 100 years is a good test of a technique.

My educated guess is that the timber is so light and so very soft that any expansion is simply absorbed as compression within that individual piece of timber.

If the end pieces of timber moved by 40mm or even 24mm, as you seem to be suggesting, then this large movement would be highly visible; in fact it would pull the nails out! This does not happen.

Originally Posted by Mumbo Jumbo

Hi All,

I am replacing my Verandah ceiling (which had old cement sheets) with treated pine (blue) tongue and groove timber boards for a more classic look. The ceiling i will replace is 1.8 meters wide by 9.5 meters long.

I will leave an expansion gap of 10mm round all sides but my question is can i go that long without dedicated expansion joints? and if so at what distances would i need to place them?

I live in Melbourne so normal temperatures for the area.

Thanks in advance

Mumbo Jumbo

Hi MJ. Why are you using treated pine? The ceiling of a verandah is quite protected and paint will protect the timber further. Surely regular VJ lining boards would be cheaper?

Originally Posted by Mountain Ash

Hi MJ. Why are you using treated pine? The ceiling of a verandah is quite protected and paint will protect the timber further. Surely regular VJ lining boards would be cheaper?

Hi MA,

You are totally correct, but I have had some slight water ingress in the verandah roof space before (now fully repaired) and didn't want to take the chance of the boards being potentially affected in the future if it happens again. Besides I'm a belt and braces kind of guy and only want to do this job once, which is why i was worrying about gaps.

I'm only a home carpentry hobbyist and I totally respect and appreciate your words of advice and the fact they you are using your experience to save me money (which is great), but for this one i will stick with the treated product.

Thanks again MA